This invention relates to techniques for generating and detecting acoustic wave energy.
Acoustic waves are utilized in a variety of different fields of technology. Underwater communications systems, for example, transmit information on acoustic frequencies. In the nondestructive testing field, acoustic wave energy is extensively employed to interrogate materials and structures for hidden defects. Acoustic techniques are widely utilized in semismic exploration to detect subsurface deposits of valuable minerals such as oil and gas. Such specific applications of acoustic waves normally require the selective detection or generation of a particular frequency or band of frequencies within the broad spectrum of acoustic frequencies. The necessary frequency discrimination may be supplied to some extent by transducers which are selectively responsive to a certain bandwidth or by electronic filters which are designed to receive a broadband signal from a transducer and pass only the desired portion of that signal in the frequency range of interest.
In many applications, however, the available devices and techniques have provided less than the optimum frequency selection. Consequently, a need has developed in the art for an apparatus and method which will provide improved frequency selection within the acoustic signal spectrum.